Pen cap or similar article



FIG. 1 is a front top perspective view of a pen cap or similar article showing my new design;

FIG. 2 is a front elevational view;

FIG. 3 is a right side elevational view, the left side being a mirror image thereof;

FIG. 4 is a rear elevational view;

FIG. 5 is a top plan view; and

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a pen cap or similar article, as shown and described. 